Denture cleanser



States The present invention relates to improvements in denture cleaners and methods of preparing the same, and more particularly to improvements in combinations of solid chemicals in mixtures that are highly useful when dispersed in liquid media for effectively and efficiently removing oral deposits including, for instance, stains from food, tobacco, or other sources; mucin; food particles; tartar and calculus.

Mixtures of solid ingredients, such as those referred to in a copending application Ser. No. 210,584, filed July 17, 1962, now abandoned, of which the present application is a continuation-in-part, including one or more solid peroxidized compounds, provide means whereby bubbling is effected in a liquid medium that serves in removing oral deposits from removable dentures. It has been found that certain metal complexes may be included in cleansing mixtures containing a peroxidized compound to obtain a catalytically increased evolution of gas for more active bubbling without detracting from desirable characteristics of such mixtures as denture cleansers.

In the above application Ser. No. 210,584, stable, substantially dry, odorless, free-flowing, non-lumping, nondeliquescent, non-hydgroscopic, compositions are disclosed for cleansing removable dentures and for removing oral deposits therefrom. Solid ingredients are mixed together in particulate or finely divided form, preferably predominantly granular, which remain free-flowing in a container, and which, when added to water, shOW no tendency to form a scum, and provide clear, non-cloudy solutions in water.

Compositions are disclosed in the above application which contain combinations consisting essentially of a mixture of dipotassium persulfate, sodium perborate, and sodium carbonate, or mixtures of sodium perborate, dipotassium persulfate, trisodium phosphate, and sodium carbonate. The following illustrate proportions in these mixtures that give good results:

Parts by weight Dipotassium persulfate 5 to 25 Sodium perborate to 50 Sodium carbonate 10 to 50 Sodium perborate 10 to 50 Dipotassium persulfate 5 to Trisodium phosphate 10 to 50 Sodium carbonate 10 to 50 The sodium perborate can be the monohydrate or the tetrahydrate. The sodium carbonate is preferably the monohydrate. The trisodium phosphate which is obtainable as fully hydrated with twelve molecules of Water, should preferably be the monohydrated or the hemihydrate.

To the above may be added other ingredients. Sodium hexametaphosphate [(NaPO may be included preferably in the glassy, crushed, unadjusted form. Other sodium met-aphosphates are mentioned in the form of (HIO where It may be 2 or more. Other useful phosphates are sodium tripolyphosphate or pyrophosphates.

Small proportions of a coloring and of a surfactant are added advantageously to a mix. Phenolphthalein provides atetlt an attractive pink coloration when in proper concentrations. A surfactant, such as Nacconol NR (sodium dodecyl benzene sulphonate) is included in proportions below that at which a foam or scum builds up when the product is mixed with water. Other surfactants may be substituted, such as, for instance, Duponol C (sodium salts of sulfated fatty alcohols, such as, sodium lauryl sulphate); nonionic surfactants, such as Triton X-100 (watersoluble iso-octyl phenoxy polyethoxy ethanol); Dowfax 9N9 (nonyl phenol-ethylene oxide condensate having 9- 10 moles of ethylene oxide). The surfactant should preferably be one of a reasonable stability in alkaline solutions, and one that is in a solid state is desirable for ease of incorporation, though this is not essential.

A colloidal silica, also in small proportions may be included to maintain a mix in free-flowing state and to prevent lumping when subjected to certain conditions. Cab- O-Sil is particularly preferred for the present composition. When distributed in Water with the formulations disclosed herein, a transparent, clear liquid is provided, since the particles are so tiny and transparent that they are invisible or hardly visible to the naked eye in the concentrations used.

Cab-O-Sil is a colloidal, submicroscopic, pyrogenic silica prepared in a hot, gaseous environment by a vaporphase, flame hydrolysis, at high temperature (around 1100 C.), of a silicon compound, such as silicon tetrachloride. It is distinct from silica gel obtained by precipitation of silicic acid from an aqueous silicate solution, and hardening of the precipitate. Silica gel, thus formed, is interally porous, whereas Cab-O-Sil has an enormous external surface area and no internal porosity.

Cab-O-Sil contains no water-soluble inorganic salts. It is of high chemical purity, low water content, and has a high degree of particle separation. The properties and composition of a grade of Cab-O-Sil are listed as follows:

Silica content (moisture-free) percent 99.0-99.7 Free moisture (105 C.) do 0.2-1.5 Ignition loss at 1000 C. (excluding moisture do 0.2-1.0 CaO, MgO do 0.000 Fe203+Al203 d0 Particle size range micron 0.015-0020 Surface area sq. m./ gm 175-200 Specific gravity 2.1 Color White Refractive index 1.55 pH (4% aqueous dispersion) 3.5-4.2 Apparent bulk density lbs./cu.ft 2.5-7.0

A finer grade of Cab-O-Sil has the above characteristics but a particle size range of 0007-0010 micron, a surface area of substantially 325 sq. m./gm., and a refractive index of 1.46.

The various grades of Cab-O-Sil may be used interchangeably.

It is found that, except for the minor ingredients such as dye or coloring, and the surfactant, it is best not to use the chemicals in a finely powdered form. It is advantageous and preferable to use them in granular form with particle sizes preponderantly between substantially 10 and 60 mesh and with a major proportion between 20 and 40 mesh. It is not found objectionable when minor fractions are somewhat larger than 10 mesh and as fine as to mesh.

The following examples designated as C and D serve to illustrate the invention in said application Ser. No. 210,584:

The following solid ingredients are mixed together in in finely divided but granular form preferably in the order listed. The preferred proportions are given in parts by weight:

Cab-O-Sil 0.5-1,0

The following ingredients, in parts by weight, are finely granulated and mixed together:

Sodium perborate 40 Dipotassium persulfate 10 Trisodium phosphate 20 Sodium carbonate 30 If desired, and for various purposes, enzymic or enzymatic agents are advantageously included in the above compositions. Catalase in the proportion of about 0.001 to 0.1 percent by weight of the composition, as well as plantderived peroxidase serve to promote gassing. Proteolytic enzymes assist in such compositions in dissolving hardened mucin in refractory denture deposits. About 0.01 to 0.02 percent by weight of the latter enzymes is effective. Pancreatic extracts and papain perform the latter function.

A half teaspoonful of the product of Example C in an eight ounce glass of water provides a solution with a pH of about 11.6 to 12. A solution of the product of Example D, similarly prepared, has a pH of about 11.5 to 12.

It has been discovered that there are metal complexes that can serve as effective catalysts for more vigorous gassing, or increased rate of evolution of gas, for use in denture cleanser products in a manner as stated and while retaining desirable characteristics mentioned. Among the complexes there are those having the general formula M [Fe(CN) (NO) wherein M is H, or where H is replaced by a variety of cations; x may be 2 to 4; y may be 1 to 6; and 2 may be 0 to 1. Also, Fe may be replaced by Co, Ni, Mn, Cu and other metals Compounds, particularly desirable for use as catalysts in the denture cleanser products, include salts of the following acids, namely, having the formulae listed below, and stable acids themselves:

Compounds that are in stable, solid form are preferred for purposes of the present invention. It is considered impractical or undesirable to use, in the denture cleanser products of the present invention, the compounds that are not stable or not solid, or that are oxidizable or break down and give off HCN (hydrocyanic acid), or undesirable odors, or that introduce undesirable constituents that are too volatile. The acid, hydroferrocyanic acid, for instance, having the formula H [Fe(CN) is a stable, white solid that is soluble in water, ethanol, methanol, and other alcohols. It provides a clear solution while effectively increasing the rate of evolution of gas in an aqueous medium when used in association with a denture cleanser containing a peroxidized compound. Its cost, however, is an item that renders it unattractive for use in a commercial denture cleanser product.

Hydrogen in the above acids is replaceable in part or completely by sodium, potassium, calcium, barium, and other alkali and alkaline earth metals, singly, or in combinations thereof, taking their valences into account.

Any element or group of elements as a radical, that functions or can function as a cation, may replace the hydrogen in the above acid formulae. Such radicals are cited 4 as NH VO, U0 M00 or W0 ions. From the standpoint of the periodic table, the H is replaceable in part or completely by a variety of cations, or metals such as those in Groups IA, 113, HA, 1113, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VII, and VIII.

The compounds contemplated for use as catalysts in the present invention are generally referred to as cyanoferrates, or prussiates, and include materials such as the nitroprussides, for instance, Na and K [Fe(CN) (NO)]. The cyanoferrate anions have desirable properties in that they effect increased gas evolution and do not decompose in an oxygen-producing medium or in strong alkaline solutions. The water-soluble ferro and ferricyanides as well as the nitroprussides produce yellow solutions and no solid precipitates in the presence of the above-described denture cleanser compositions. Furthermore, in their use as catalysts and after an initial period of their presence for twenty-four hours in a cleansing solution, further addition of denture cleanser material to the solution produces renewed accelerated active gassing.

Several commercial brands of Prussian blue provide very good gassing with the above denture cleanser, as do Turnbulls blue freshly prepared from ferrous sulphate and potassium ferricyanide. A precipitate is formed with them and similar compounds because their cations appear in the denture cleanser solution in solid form by double decomposition with active components of the denture cleanser while the anions go into solution as soluble prussiates.

Besides the above cyanoferrates, there are mentioned other compounds which involve complex iron cyanides of aliphatic bases, of aromatic bases, of heterocyclic bases, of alkaloids, and of other basic compounds. In general, the organic ferrocyanides are also colored crystalline compounds which are usually infusible, insoluble or slightly soluble in cold water, and relatively stable at room temperature. Ferrocyanides of diamino compounds tend to be relatively unstable and more insoluble.

Among the cyanogen compounds, those with iron in the anion are to be recommended. Of the hexacyano compounds, the ferrocyanides, including ferrocyanic acid, H. [Fe(CN) are preferred over the ferricyanides, including ferricyanic acid, H [Fe(CN) for use in the products of the present invention. The ferrocyanides are more stable and cheaper. The ferricyanides are generally less stable and more expensive. Incidentally, in the case of cobalt, the reverse is true as to stability, cobalto cyano complexes being less stable than the cobalti.

The most desirable hexacyano compounds are the soluble alkali prussiates including sodium and potassium ferrocyanides. These form substantially permanent, clear solutions with a pleasing yellow color, in the presence of the required proportion of the denture cleanser material in water. Ammonium ferrocyanide is mentioned but its liberation of ammonia is not always desirable.

The prussiates vary considerably as to solubility. Both the soluble and insoluble cyano ferrates are generally equally effective catalytically. The insoluble ones chemically react with alkaline solution of a cleanser mix in such a fashion that a soluble prussiate is formed from the anionic portion of the insoluble catalyst and the alkali components of the cleanser mix, soluble ferroor ferricyanide being formed depending on the derivation and origin of the insoluble catalyst. For instance, if a blue, solid catalyst is made from a water-soluble ferrocyanide, then a ferrocyanide is formed in the cleanser solution. If an insoluble blue is made from a soluble ferricyanide then a water-soluble ferricyanide is formed by reaction with'the cleanser solution. In either case, the polyvalent metal comprising the cation of the insoluble blue is split off in the denture cleanser solution with formation of the corresponding hydroxide, carbonate, phosphate, or mixture thereof, depending on what anions are represented in the denture cleanser solution.

Among the water-soluble prussiates, calcium ferrocyanide, Ca [Fe(CN) provides good gassing; barium ferrocyanide, Ba [Fe(CN) provides very excellent gassing; calcium potassium ferrocyanide, CaK [Fe(CN) provides excellent gassing, but in each case a fiuocculent precipitate keeps rising in the denture cleanser solution during gassing.

Where desired gassing and other results are obtainable, but turbidity, or cloudiness is found objectionable, as in the use of prussiates as the catalysts and in which H of the acids is partially or wholly replaced by calcium or other alkaline earth or other polyvalent metal, for example, CaK [Fe(CN) with which only slight turbidity in a cleanser solution is likely, such turbidity is lessened or prevented by appropriately changing the denture cleanser formulation to include a sequestering agent such as hexametaphosphate, tripolyphosphate, or pyrophosphate, or even EDTA (ethylenediamine tetraacetic acid) or related chelating agents.

It is advantageous to use catalysts, or catalyst mixtures that have the least amount of Water of crystallization.

This is also preferred as to other constituents of the denture cleanser. The reasons are mainly that caking of the cleanser product is prevented, and premature catalysis or local decomposition is substantially avoided, leading to increased shelf-life of the denture cleanser product. In general, the insoluble prussiates are advantageous in this respect because they are usually free of water of crystallization.

Solid cleanser mixes of the present invention contain solid catalysts that may be soluble or insoluble in water. When any of such solid mixes is introduced into Water for cleansing a denture, the water-soluble constituents, including a peroxidized compound such as perborate or persulfate or percarbonate, proceed to go into solution, and the bubbling or gassing commences. While the catalyst continues to be in a solid state the catalytic effect is most pronounced and the evolution of gas is most vigorous for a given catalyst. Such evolution takes place most vigorously at the points of contact between the solid particles and the liquid. Around each solid particle of catalyst, the action is localized and there is a zone or layer that has the highest concentration of catalytic material in a given system, and therefore the catalytic effect is greatest in such zone or layer closest to the catalyst surfaces, thereby providing a lively local gas evolution which in general prevents caking of the soluble constituents of the cleanser in the cleansing operation. These conditions continue so long as prussiate anion is still contained in the solid particles of catalyst in the cleansing solution. The bubbling continues to be most vigorous in the initial stage while the catalyst is in process of dissolving. After prussiate anion-containing solid particles of a catalyst are no longer present, the catalytic effect is lessened, and bubbling or gassing continues but it is less vigorous for a period and finally ceases when all the peroxidized material is exhausted. In other words, a gradual diffusion takes place, gassing is initially accelerated, and ultimately becomes more uniform and continuous.

With certain mixed catalysts, a cyano ferrate or metal cyanogen complex of low solubility may be mixed with one of higher solubility so that a more highly vigorous evolution of gas is initially obtained. This is found useful especially in tablets containing the ingredients of a denture cleanser including a peroxidized compound plus a catalyst mixture which will cause an initial gassing of sufficient vigor to disrupt or disintegrate such tablets when placed in water. In tablets, this can also be brought about by mixing with a ferrocyanide catalyst that is included in a denture cleanser solid mix, a small proportion of complexes of EDTA salts with a heavy metal (iron, manganese, copper, or cobalt), or a cobaltic nitrite, or a cobalti cyanide. The initial catalytic effect desired may be predetermined by the nature of a catalyst or by the ratio of a more active catalyst to a less active catalyst in a catalyst mixture.

A single catalyst compound may be mixed with a denture cleanser composition in the proportion by weight of substantially 0.1 to 1% (or up to 5%) of the total cleanser composition. The total proportion of the abovedescribed catalyst mixture, on the other hand, may be as low as 0.01 to 0.2 percent of the total cleanser mixture by weight. The size of the soluble catalyst particles ranges preferably from 20 to 60 mesh, or even 20 to mesh, while the water-insoluble catalysts, being often colloidal in nature, may comprise particle sizes as small as several microns or a fraction of a micron.

The following examples serve to illustrate the present invention:

Example 1 Parts by weight Sodium perborate 30 Potassium persulfate 2-0 Trisodium phosphate 30 Sodium carbonate 20 Phenolphthalein 0.01 Nacconol NR 0.04 Sodium hexametaphosphate 0.25 Cab-O-Sil 0.5 Prussian blue 0.1

When the above mixture is added to about 8 ounces of warm water in the amount of about /2 teaspoon, the water is at first colored violet, then it changes to magneta, then to pink, and finally becomes colorless. A very small amount of pale tan fiocculent solid appears eventually in the solution. The gas evolution in the cleansing solution is excellent.

Example 2 Parts by weight Sodium perborate 30 Potassium persulfate 20 Trisodium phosphate 30 Sodium carbonate 20 Phenolphthalein 0.01 Nacconol NR 0.2 Sodium hexametaphosphate 0.25 Cab-O-Sil 0.5 Potassium ferricyanide 0.5

One half teaspoon of the above mixture is added to about 8 ounces of warm water (approximately 'F.). The water is colored a rose pink in the beginning, then the color changes to a lighter pink, and eventually the solution becomes clear and faintly yellow. The gas evolution is very excellent.

Example 3 A formulation similar to that in Example 1 is provided except that the Prussian blue as catalyst is replaced by 1 part by weight of sodium nitroprusside. The initial color of the solution after addition of the cleanser composition is an orange pink which gradually turns to a pinkish tan and eventually to a clear, intense yellow. The gas evolution is extremely vigorous, especially in the beginning.

The solution, after addition of /2 teaspoonful of the above mixture to about 8 ounces of warm water becomes a strong pink which eventually in time fades out to colorless. The gassing is very good in the beginning and especially when there is still solid salt in the container adjacent to the bottom.

Example Parts by weight On addition of /2 teaspoon of the above mixture to warm water, the solution turns an intensive pink, and very excellent gas evolution starts immediately. The gas bubbles are very fine and a foam layer appears at the surface of the liquid, because of the relatively high concentration of the surfactant. Occasional stirring is helpful in breaking up the foam layer and in expediting clarification of the liquid. Within 20 minutes the pink color disappears and the solution is crystal clear.

Example 6 Par-ts by weight Trisodium phosphate 20 Sodium hexametaphosphate (adjusted) 20 Sodium perborate 20 Sodium carbonate 20 Potassium persulphate 20 Phenolphthalein 0.02 Duponol C 0.1 Cab-O-Sil 0.5 Calcium potassium ferrocyanide 0.1

The same observations are made in this example as in Example 5, except that gas evolution is somewhat less vigorous and the foam layer is less dense and less in volume than that observed in Example 5.

A denture to be cleaned is introduced in a water solution serving as the cleanser and is permitted to remain therein for a relatively short time. The denture is removed and washed with fresh water and inserted in the mouth. The cleanser is distinctive in that no after-taste is noticeable on a denture so treated. The color from the indicator usually fades within twenty-four hours and this serves as a warning that the solution has been used and that it is no longer sufiiciently fresh for reuse. Certain of the ingredients, such as the perborates, act as strong disinfectants, and the treatment of dentures :as described tends to counteract denture breath that develops when the dentures are in use.

In the use of the above-described products in cleansing dentures, a denture to be cleansed may be left in a solution of the selected composition for as long as desired without injury to the denture. One-half hour to one hour or less is usually sufiicient to obtain thorough cleansing. Brushing of a denture with the solution is not necessary and should be avoided Where certain plastics used in a denture structure are likely to be injured thereby. Application of a solid cleanser or of a solution thereof and rubbing of the denture by hand are generally sufficient for softening and removing scaly debris in the most ditficult instances.

What is claimed is:

1. A denture cleanser having a peroxy oxygen-liberating compound for evolving gas bubbles in an aqueous medium, and an activating agent having the radical consisting of [Fe(CN) (NO) in which the iron may be replaced by a metal selected from a group consisting of cobalt, nickel, manganese, and copper, and wherein y=1 to 6, and 2:0 to 1, the said activating agent being present in amount sufiicient to promote increased evolution and bubbling of gas.

2. A denture cleanser composition'consisting essentially of a mixture of sodium perborate, potassium persulfate, and sodium carbonate, which mixture generates gas bubbles when added to water, and an activating agent distributed in said mixture in amount sutficient to promote increased evolution and bubbling of gas, the said activating agent having the radical consisting of in which the iron is replaceable by a metal selected from a group consisting of cobalt, nickel, manganese, and copper, and wherein y=1 to 6, and z=0 to 1.

3. A denture cleanser having a peroxy oxygen-liberating compound for evolving gas bubbles in an aqueous medium, and an alkali metal prussiate in amount sulficient to promote increased evolution and bubbling of gas.

4. A denture cleanser consisting essentially of a mixture of 10 to 50 parts by weight of sodium perborate, 5 to 20 parts by Weight of potassium persulfate, 10 to 50 parts by weight of trisodium phosphate, 10 to 50 parts by Weight of sodium carbonate, and a metal cyanoferrate, selected from a group consisting of alkali and alkaline earth cyanoferrates, in the proportion of substantially 0.01 percent to substantially 5 percent of the total cleanser mixture by weight.

5. A denture cleanser consisting of a mixture of 30 parts by Weight of sodium perborate, 20 parts by weight of potassium persulfate, 30 parts by weight of trisodium phosphate, 20 parts by weight of sodium carbonate, 0.01 part by weight of phenolphthalein, 0.2 part by Weight of sodium dodecyl benzene sulphonate, 0.25 part by weight of sodium hexametaphosphate, 0.5 part by weight of a suhmicroscopi-c pyrogenic silica prepared at high tem-' perature by vapor phase hydrolysis of silicon tetrachloride, and 0.5 part by Weight of potassium ferricyanide.

6. A denture cleanser consisting of a mixture of 30 parts by weight of sodium perborate, 20 parts by weight of potassium persulfate, 30 parts by weight of trisodium phosphate, 20 parts by weight of sodium carbonate, 0.02 part by weight of phenolphthalein, 0.02 part by weight of sodium dodecyl benzene sulphonate, 0.45 part by weight of sodium hexametaphosphate, 0.8 part by weight of sodium chloride, 1.0 par-t by Weight of a submicroscopic pyrogenic silica prepared at high temperature by vapor phase hydrolysis of silicon tetrachloride, and 0.2 part by weight of potassium ferricyanide.

References Cited UNITED STATES PATENTS 1,324,764 12/1919 Wald 25297 X 1,894,277 1/1933 Manahan 25299 X 2,498,344- 2/1950 Rider et al. 25299 X 2,576,205 11/1951 Apperson 25299 2,932,556 4/1960 Stephanou 252385 X 2,975,139 3/1961 Kaufimann et al 25299 LEON D. ROSDOL, Primary Examiner.

SAMUEL I-I. BLEOH, Examiner.

M. WEINBLATT, Assistant Examiner. 

1. A DENTURE CLEANSER HAVING A PEROXY OXYGEN-LIBERATING COMPOUND FOR EVOLVING GAS BUBBLES IN AN AQUEOUS MEDIUM, AND AN ACTIVATING AGENT HAVING THE RADICAL CONSISTING OF (FE(CN)Y(NO)Z) IN WHICH THE IRON MAY BE REPLACED BY A METAL SELECTED FROM A GROUP CONSISTING OF COBALT, NICKEL, MANGANESE, AND COPPER, AND WHEREIN Y=1 TO 6, AND Z=0 TO 1, THE SAID ACTIVATING AGENT BEING PRESENT IN AMOUNT SUFFICIENT TO PROMOTE INCREASED EVOLUTION AND BUBBLING OF GAS. 